Antioxidants for mineral oil lubricants and compositions containing the same



amoeba 24, 1950 ANTIOXIDANTS FOR MINERAL CANTS AND COMPOSITIONS C THE SAME orrics on. wanton AINING .Herschcl a. Smith, Wallingford, and Troy 1..

Can Audubon, N. 1.,

Lansdowne, Pa and John G. Peters, assignors to Gulf Oil corpora tion, Pittsburgh, Pa., a corporation of Pennsyl- No Drawing. Application November i7, 189, Serial No. 127,992

18 Claims. (Cl. ZSH'LS) 1 This invention relates to antioxidants fo mineral oil lubricants and compositions containing the same, and more particularly, it relates to addition agents for mineral oil lubricants which inhibit the oxidative deterioration of said lubricants.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, plain mineral lubricating oils often prove unsatisfactory in service because of the oxidative deterioration of the oil, with the attendant deposition on the engine surfaces of varnish, gum or sludge. Furthermore; many lubricating oil compositions which may be highly satisfactoryfor the lubrication of other mechanisms have been found wholly unsuitable for use as, turbine oils.

The formation of varnishes, gums and sludges on engine surfaces is due at least in part to oxidation effects on mineral lubricating oils. In turbine oils the problem of oxidation .is further aggravated, because in .normal use. turbine oils rapidly .become contaminated with water.

It is an object of this invention, therefore, to

provide an addition agent for mineral oil lubricants which will inhibit the oxidative deterioration of such lubricants.

activated clay as a catalyst, and recovering the" condensation product. The condensation product so obtained is a liquid product which, when added to mineral oil lubricants, confers an excellent stability against deterioration by oxidation. In addition, bearing corrosion inhibiting properties are conferred on the oil. Such condensation products and, the mineral oil lubricant compositions containing them are believed to be novel and are considered parts of our invention.

Contrary to what may be expected from the nature of the reactants, we do not obtain highly condensed, insoluble resinous products. On the contrary, wh n the above reactants are condensed in accordance with our invention, there areobtamed liquid condensation products which are non-resinous and which are readily soluble in mineral oils.

In performing 111s condensation, the reactants are mixed and heated to a maximum temperature of 350' 1''. We have found that if the temperature of 350 1''. is exceeded to any substantial extent, the condensation product formed tends to be resinous and insoluble. In general, the preferred temperature for the condensation ranges from to 300 F.

The proportions of the reactants vary as follows. The di (alkylphenol) sulfide is employed in an amount of 1 mol, N-dimethylaniline in an amount of from 1 to 2 molswand formaldehyde in an amount of from 1 to 2 mols. Ordinarily, it

is preferred to use from 5to 10 per cent by weight of the activated clay catalyst, based on the total weight of the reactants. However, smaller amounts, as low as 1 per cent by weight, and

larger amounts, as high as 20 per cent by weight,

may also be employed; but larger amounts than about 10 per cent by weight are ordinarily not necessary.

The di (alkylphenol) sulfldesused in preparing our new compounds have the formula on 08 E ]-s.-[ J a a where R is an alkyl group of from 4 to 12 carbon alkylating phenol with suitable olefins' in the' presence of concentrated sulfuric acid as a catalyst. A preferred alkyl phenol is p-tetramethylbutyl phenol obtained by alkylating phenol with diisobutylene, and the monoand di-(isofiuxed for a period of hours.

- lysts in accordance with our invention. Such materials are well known in the art and comprise" a natural clay, such as bentonite, fuller's earth, montmorillonite, fioridin and smectite, which has been acid treated in order to activate the clay. Such materials are described in U. 8. Patent 1,898,165, for example. A preferred activated clay is activated montmorillonite sold under the nam of Filtrol.

In preparing our new addition agents, the reactants and catalysts are placed into a reaction vessel which is then closed andthe mixture heated with agitation under reflux until all of the formaldehyde or formaldehyde-yielding compound, has been consumed. At this time, the water which is formedas a result of the condensation is removed, preferably under'vacuum. and the dehydrated condensation product is then filtered to remove the activated clay catalyst. In

:some instances, it is desirable to prepare our new addition agent in a concentrate in a mineral lubricating oil which may then be diluted with additional oil to. the concentration desired in the final lubricating composition. In such instances,

the mineral lubricating oil may be added in a suitable amount, say in a weight equal to the weight of reactants, to the reaction mixture in the reaction vessel, and the condensation product obtained will then be a concentrated solution of the addition agent in the mineral lubricating oil.

The condensation products obtained in accordance with our invention are non-resinous liquids.

While the exact nature of the chemical composition of the condensation products is unknown, all of the three reactants enter into a final unitary product. The exact manner in which the catalyst influences the reaction is unknown. However, regardless of any theoryinvolved, the use of an activated clay catalyst is an essential feature, of.

our invention, since if the catalyst is omitted, black, insoluble, resinous condensation products are obtained.

The following examples illustrate the preparation of our new addition agent. Unless otherwise indicated, all parts are by weight.

Y Example I.--Into a stainless steel reaction vessel, there were charged 442 parts of di (isooctylphenol) sulfide, 242 parts of N-dimethylaniline, 68 parts of activated montmorillonite.

(Flltrol) and 170 parts of a 3'7 per cent by weight aqueous solution of formaldehyde. The reactants were inthe molar proportions of 1 mol of the di (iso-octylphenol) sulfide, 2 mols of the N-dimethylaniline and 2 mols of the formaldehyde. The mixture was heated with agitation and re- Thereafter, the temperature was raised to 280 F. and all water, both that added with the formaldehyde and formed in the reaction. was distilled off. The

octylphenol) sulfides obtained therefrom are I 4 dried product was filtered and had the following properties:

Gravity, API 8.7, Sulfur. per cent "4.0 Neutralization No 3.1

Example II.Three hundred fifty-eight (358) parts of di-(t-amylphenoli sulfide, 242 parts of N-dimethylaniline, 68 parts of activated montmorillonite (Filtrol) andl'lO parts of a 37 per cent by weight aqueous solution of formaldehyde were placed into a stainless steel reaction vessel. The

reactants were in the molar proportions of 1 mol of the di (t-amylphenol) sulfide, 2 mols of the- N-dimethylaniline and 2 mols of the formaldehyde. The vessel was then closed and the mixture heated with agitation and refluxed for 5 .hours. The temperature was then raised to 280.

F}. to distill off all water, thereby dehydrating the liquid product. The product was then filtered and had the following properties:

Gravity, API 5.1 Sulfur, per cent 5.7 Neutralization No 3.4

Example I[I.Into a stainless steel reaction vessel, there were charged 442 parts of di isooctylphenol) sulfide, 121 parts of N-dimethylaniline, 34 parts of activated montmorillonite '(Filtrol) and 170 parts of a 3'? per cent by weight aqueous solution of formaldehyde. The reactants we're inthe molar proportions of 1 mol of the di (iso-octylphenol) sulfide, 1 mol of the N- dimethylaniline and 2 mols of the formaldehyde. The reactants were reacted under theconditions shown in Example I. The liquid reaction product had the following properties:

Gravity, API 5.9 Sulfunper cent 9.8 Neutralization No 4.9

The condensation products obtained in accordance with the above disclosure from di (alkylphenol) sulfides, N-dimethylaniline and formaldehyde in the presence of an activated clay catalyst are excellent addition agents for mineral oil lubricants. They are readily soluble in all types of mineral oils, that is paramnic, naphthenic or mixed base mineral oils and can be blended with mineral oils in high proportions to form concentrated solutions thereof, which may then be diluted down to the proportions desired in the final mineral oil lubricant composition. As stated,

our new addition agents are remarkably effective in inhibiting the oxidative deterioration of mineral oil lubricant compositions. For this purpose, small amounts of our new addition agents are generally sufilcient. For example, our addition agents may be added to mineral lubricating 00.

oilsin minor amounts, say from 0.1 to 10 per cent by weight on the mineral oil, sufficient to inhibit the oxidative deterioration of the oil. Larger amounts of our new addition agents may be used if desired but it is ordinarily unnecessary to do so. In addition, to inhibiting oxidative deterioration, our new addition agents are also effective bearing corrosion inhibitors.

The following examples illustrate the advantageous eflects of our new addition agents. In the following examples, the base oil and the same oil blended with our new addition agents are subjected to a standard oxidation test which measures the stability of the oils to oxidation. The oxidation test referred to is a standard test designated ASTM D943-47T. Briefly, the test comprises subjecting the oil sample to oxygen at a temperature of 95 0. (203 F.) in the presence 01' water and an iron-copper catalyst, and determining the time required to build up a neutralization number of 2. The flow of oxygen is maintained at 3 liters pe hour. The effective stability to oxidation mineral oil lubricant compositions containing our new addition agents is illustrated by the results shown in the following examples.

Example IV.-A turbine lubricating oil was blended with 0.5 per cent by volume of the additive prepared according to Example I. A comparison of the base'oil and improved oil showed Eggcmple V. A turbine lubricating oil was blended with 0.5 rper cent by volume of the compound of Example II. The blended and unblended oil had the following properties:

Base Oil gg Gravity, API. 25. 2 29. 2

Color, NPA 2. 75 3. 0

Neutralization N 0. 02 0. 03 Oxidation Test, ASTM D943-47T: Time Oxidized, Hr. for Neut. No. oi 2.0 90 1,600

,The above examples show the notable oxidation stability imparted to mineral oil lubricant compositions by the use of our new addition agents. Mineral oil lubricant compositions containing our new addition.agents are therefore eminently suited for use where the operating conditions are extremely severe, as in Diesel, tank and truck engines, and in the lubrication of steam turbines.

The effects of our new addition agents cannot be readily accounted for and cannot be predicted from the nature of the reactants. Thus, condensation, products prepared from other functionally similar compounds have been found to be either pro-oxidant or to show no antioxidant effects whatsoever. For example, we have prepared condensation products similar to our new addition agents by substituting aniline for the dimethylaniline. The resulting condensation products were found to be entirely unsuitable for inhibiting the oxidative deterioration of mineral oil lubricant compositions.

While we have shown in the examples the preparation of compounded lubricating oils, our invention is not limited theretobut comprises all mineral oil lubricant compositions containing our new addition agents, such as greases and the like. If desired, other known addition agents may be incorporated into the lubricant compovariations as fall within the spirit or the inveit tion and the scope of the appended claims.

We claim:

1. The'process oi preparing an addition agent for mineral oil lubricants which comprises heating 1 mol of a di (alkylphenol) sulfide having the rormula on on i: O a s wherein R is an alkyl group of from 4 to 12 carbon atoms and :c is an integer from 1 to 2, 1 to 2 mols of N-dimethylaniline, and 1 to 2 mols of formaldehyde in the presence clay catalyst at a temperature not in excess of 350 F. to condense together the three reactants, and recovering the condensation product.

2. The process of preparing an addition agent for mineral oil lubricants which comprises heating 1 mol of a di (allwlphenol) sulfide having the formula 0H 0H E 14.1 J

wherein R is an alkyl group oi from 4 to 12 car- 5 the formula sitions prepared in accordance with our invention. For example, pour point depressants, ex-

treme-pressure agents, viscosity index improvers and the like may be added.

Resort may be had to such modifications and bon atoms and a: is an integer from i to 2, 1 to 2 mols of N-dimethylaniline, and 1 to 2 mols of iormaldehyde in the presence of an activated ciaycatalyst at a temperature of from 150 to 300 F. to condense together the three reactants, and recovering the condensation product.

3. The process of claim 1, wherein a: is 2 and R is the iso-octyl radical.

4. The process of preparing an addition agent for mineral oil lubricants which comprises adding 1 mol of a di (alkylphenol) sulfide having on OH wherein R is an alkyl group of from 4 to 12 carbon atoms and a: is an integer from 1 to 2, 1 to 2 mols of N-dimethylaniline, 1 to 2 mols of formaldehyde and from 5 to 10 per cent by weight on the foregoing reactants of an activated clay catalyst to a mineral lubricating oil, heating the mixture at a temperature of from 150 to 300 F. to condense together the three reactants, and recovering a solution of the condensation product in the mineral lubricating oil.

5. The process of preparing an addition agent 'for mineral oil lubricants which comprises heating 1 mol of di (iso-octylphenol) sulfide, 2 mols of N-dimethylaniline and 2 mols ofiormaldehyde in the presence of an activated clay catalyst at a temperature of from 150 to 300 F. to condense together the three reactants, and recovering the condensation product.

6. The process of preparing an addition agent for mineral oil lubricants which comprises heating 1 mol of di (t-amylphenol) sulfide, 2 mols of N-dimethylaniline and 2 mols of formaldehyde in the presence of an activated clay catalyst at a temperature of from 150 to 300 F. to condens together the three reactants, and recovering the condensation product.

. 7. The process oi preparing an addition agent for mineral oil lubricants which comprises heating 1 mol of di (iso-octylphenol) sulfide, 1 mol oi N-dimethylaniline and 2 mois or formaldehyde in the presence of an activated clay catalyst at a temperature offrom 150 to 300 F. to condense together the three reactants, and recovering the condensation product.

8. A non-resinous condensation product of,1

mol oi a di (alkylphenol) sulfide having the formula on on L s J wherein.R is an alkyl group of from 4 to 12 carbon atoms and a: is an integer from 1 to 2.-

l to 2 mois of N-dimethylaniline and 1 to 2 mois of formaldehyde, said product being obtained by the process of claim 1.

9. The product of claim 8, wherein a: is 2 and R is the iso-octyl radical.

10. A non-resinous condensation product of 1 mol of di (iso-octylphenol) sulfide, 2 mois of N-dimethylaniline and 2 mols of formaldehyde, said product, being obtained by the process or claim 5. 1

11. A non-resinous condensation product of 1 mol of di (t-amylphenol) sulfide, 2 mois of N-dimethylaniline and 2 mois of formaldehyde,

OH OH O O B R wherein R. is an alkyl group of from 4 to 12 carbon atoms and a: is an integer from 1 to 2, 1 to 2 mois or N-dimethylaniline and 1 to 2 molsof formaldehyde, said product being obtained by the process of claim}.

14. The composition-of claim 13, wherein -:c

is 2 and R is the iso-octyl radical.

n15. A lubricant composition comprising a major amount of a mineral lubricating oil, and

a minor amount, from 0.1 to 10 per cent by weight of said oil, of a non-resinous condensation product of 1 mol of a di (alkylphenol) sulflde having the formula wherein R. is an alkyl group of from 4 to 12 carbon atoms and :ris an integer from 1 to 2, 1 to 2 mois of N-dimethylaniline and 1 to 2 mois of formaldehyde,-said product being obtained by the process of claim 1.

16. A lubricant composition comprising a major amount of a mineral lubricating oil, and a minor amount, sufllcient to inhibit the oxidative deterioration of said oil, of a non-resinous condensation product of 1 mol of di (iso-octylphenoi) sulfide, 2 mols of N-dimethylaniline and 2 mois of formaldehyde, said product being obtained by the process of claim 5.

17. A lubricant composition comprising a major amount or a mineral lubricating oil and a minor amount, sumcient to inhibit the oxidative deterioration of said 011, of a non-resinous condensation product of 1 mol of di (t-amylphenol) sulfide, 2 mols of N-dimethylaniline'and 2 mois of formaldehyde, said product being obtained by the process of claim 6.

18. A lubricant composition comprising a major amount oi a mineral lubricating oil, and a minor amount, sumcient to inhibit the oxidatlve deterioration of said oil, of a non-resinous condensation product of 1' mol of di (iso-octylphenol) sulfide, 1 mol of N-dimethylaniline and 2 mois of formaldehyde, said product being obtained by the process of claim 7.

HERSCI-EL G. SMITH. TROY L. CAN'I'RELL. JOHN G. PETERS.

No references cited. 

1. THE PROCESS OF PREPARING AN ADDITION AGENT FOR MINERAL OIL LUBRICANTS WHICH COMPRISES HEATING 1 MOL OF A DI (ALKYLPHENOL) SULFIDE HAVING THE FORMULA
 13. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL, AND A MINOR AMOUNT, SUFFICIENT TO INHIBIT THE OXIDATIVE DETERIORATION OF SAID OIL, OF A NON-RESINOUS CONDENSATION PRODUCT OF 1 MOL OF A DI (ALKYLPHENOL) SULFIDE HAVING THE FORMULA 